The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
300 Calorie Meals For Weight Loss — UK Health Guide
Low-calorie meal planning is a proven weight loss strategy, but 300 calorie meals alone may not be sustainable long-term for everyone. In the UK, prescription weight loss medication is now available to eligible adults as part of a comprehensive weight management approach. This guide explores how small meals fit into broader weight loss strategies — alongside lifestyle changes and, where appropriate, evidence-based prescription options. Check your BMI and eligibility using our free BMI calculator, and explore whether prescription weight management might support your individual goals.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK Prescription Weight Loss Options For Eligible Adults
If you're struggling with weight loss despite eating smaller meals, prescription weight loss medication may be available to you in the UK. Mounjaro (tirzepatide) and Wegovy (semaglutide) are both licensed for weight management in UK adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes or high blood pressure. Saxenda (liraglutide) is also available as a daily injection option. Clinical trials show these medications may help reduce appetite and support a calorie deficit — making adherence to lower-calorie eating patterns like 300 calorie meals more manageable. A reduced-calorie diet combined with increased physical activity alongside medication typically produces better results than diet alone. Our free GLP-1 weight loss calculator can help you estimate potential outcomes at different doses if you're eligible.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access — How To Find Out If You're Eligible
In the UK, weight loss medication is available through both NHS specialist services and private prescribing. NHS access: referral to a tier 3 weight management service through your GP, though waiting lists vary significantly by region. Private access: consultation with a licensed UK prescriber online, usually faster. Your GP can assess your eligibility based on your BMI and health conditions. Even if you're planning to eat smaller, 300 calorie meals, speaking to your GP about your weight management goals is important — they can advise whether prescription support is right for you and help rule out any underlying health issues affecting your weight. Track your progress using our free progress tracker to monitor your results alongside any treatment plan.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Can I lose weight eating only 300 calorie meals?
Eating 300 calorie meals can create a calorie deficit, but sustainability varies. A typical adult needs 1800–2500 calories daily. Eating only 300 calories is very restrictive and should only be done under medical supervision. Most UK health guidance recommends a deficit of 500 calories daily for sustainable loss of about 0.5kg per week. Combining reasonable meal portions with prescription weight management may be more sustainable.
What is the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only injections licensed for weight management in the UK. Mounjaro (tirzepatide) works on two hormone pathways and may produce slightly higher average weight loss in clinical trials (~20% body weight). Wegovy (semaglutide) acts on one pathway (~15% average). Both require weekly injections and must be prescribed following clinical assessment. Individual results vary significantly.
Is prescription weight loss medication available on the NHS?
Yes, Mounjaro, Wegovy, and Saxenda are available on the NHS through specialist tier 3 weight management services. Access requires a referral from your GP and assessment by a specialist team. Availability and waiting times vary significantly by region (ICB). Private prescribing is also available if you don't want to wait or aren't referred to NHS services.
How do 300 calorie meals work with weight loss medication?
Prescription weight loss medication works by reducing appetite and food cravings, making it easier to stick to smaller meals and lower-calorie eating patterns. Rather than forcing yourself to eat tiny portions, the medication helps you feel fuller sooner. Combining medication with a balanced, modest-calorie diet (not extreme restriction) and increased physical activity produces better long-term results.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, etc.) may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults have lower thresholds. Your GP or a licensed prescriber will assess your individual eligibility. Weight management UK services can advise if you're unsure.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.